Was she able to log in before she changed her password? If so, have her try logging in with her old password. It's possible that she had only changed her forum password, rather than the actual game password, in which logging in with the new password into the game would not work. If she tried changing her password through the "Profile" tab on the forum, this will not change her game password. To change your game password, you can go to the Forgot Your Password function, located inside of the golden box on the website, have an e-mail sent to the email address that you signed the account up with, and change the password from there.
Be sure that her username doesn't exceed the 16 character limit, as well, as this can cause her not to be able to connect to the server.